He is in the vent. He hide there so Kanaya would not kill him for murdering her friends. That scene is from Act 6 Intermission 3. Saying just about anything else about that scene would be giving away BIG spoilers, :D
i watched this before the update on the 9th so when i saw the 1st pic was like wait when did this happen then i went to the website and i was like oooooo so thats were it came from